Method of making tooth-crowns.



EMIL MOHR, OF COLOGNE, GERMANY.

METHOD OF MAKING -TOOTH-CROWNS.

No Drawing.

Specification of Letters Patent.

Application filed August 22, 1910. Serial No. 578,439.

Patented Apr. 4, 1911.

'0 all whom it may concern:

Be it known that I, EMIL MOHR, a sub ject of the King of Prussia, German Emperor, residing at Cologne, in the Province of the Rhine, Kingdom of Prussia, German Empire, have invented certain new and use ful Improvements in Methods of Making Tooth-Crowns, of which the following is a description.

My invention relates to improvements in the method of making seamless metallic tooth crowns.

In carrying out my invention, I, firstly, separate the tooth to be provided with the crown from the adjacent teeth in such a manner that the spaces are exactly sufficient for receiving the metal of the crown. For this purpose, not only the points of contact but also the whole side faces of the tooth must be ground off corresponding to the thickness of the crown metal. I prolong the shank of the tooth form for the purpose of allowing the crown to be pushed into the gum around the tooth. Now, I surround the tooth form with a rubber tube leaving the masticatory face of the tooth form fully un covered. The said rubber tubes are an essential feature of my invention. The dentist must have a store of tubes of various sizes and thicknesses corresponding to the various teeth to be coated and to the different walls of metallic crowns. The tooth form covered with india rubber is, then, placed on the bottom of a mold, and metal easily to be rendered fluid is cast around the form. After the metal is cooled, it is removed from the mold, and the matrix thus gained is divided into two sections by any suitable tool so that the inclosed tooth form can dro out. The blank of gold or other metal use for making tooth crowns is placed in the cavity of the matrix and swaged therein to cause it to conform to the surface configuration of the tooth. The crown is now ready for being placed upon the tooth. Be-

fore doing so, it is necessary to grind off all such parts of the tooth that correspond to the parts of the form which were not covered by the rubber tube. Particularly the masticatory face of the tooth must be removed accordin to the thickness of the crown metal. If the diameter of the tooth essentially diminishes toward the root, it is also necessary to grind off the protruding parts of the tooth for allowing the crown to slide at its place. The circular parts of the crown metal will then correspond to the rubber coat of the tooth form thus securing an exact contact of the tooth with the adjacent teeth. The masticatory parts of the metal crown have the place of the corresponding parts of the tooth which are ground off so that they fully comply with the requirements of the so called articulation.

Having thus described my invention and its use, I claim 1. The method of making seamless metallic tooth crowns, which consists in grinding the side faces of the tooth to the thickness of the crown metal, surrounding the tooth form with a rubber tube and then molding the metal therearound.

2. The herein described method of making seamless metallic'tooth crowns which consists in surrounding the tooth crown with a rubber tube, placing the same in a mold, casting a metal therearound, placing a blank of sheet metal for making the crown in a cavity' of a matrix, and swaging the same therein. 4

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

EMIL MOHR.

Witnesses:

' HERMAN F. BUDDE,

BERNARD A. Boone.

Copies of this patent may be obtained for flve cents each, by addressing the Commissioner of Patents, Washington, D. O. 

